From the Guidelines
Hematuria, or blood in the urine, can be caused by a variety of factors, including urinary tract infections, kidney stones, kidney diseases, bladder or kidney cancers, and prostate problems in men, as noted in the study by Wolfman et al 1. The causes of hematuria can be divided into nephrogenic and urogenic causes, with renal parenchymal disease being the most common benign nephrogenic cause, and urolithiasis, infection, and benign prostatic hypertrophy being common benign urogenic causes, as stated in the study by Wolfman et al 1. Some of the key factors associated with the development of a urinary malignancy include gross hematuria, male gender, age >35 years, smoking, occupational exposure to chemicals, analgesic abuse, history of urologic disease, irritative voiding symptoms, history of pelvic irradiation, chronic urinary tract infection, exposure to known carcinogenic agents or chemotherapy, and chronic indwelling foreign body, as listed in the study by Wolfman et al 1.
Common Causes of Hematuria
- Urinary tract infections (UTIs)
- Kidney stones
- Kidney diseases
- Bladder or kidney cancers
- Prostate problems in men
- Certain medications, such as blood thinners like warfarin or aspirin
- Intense exercise or trauma
- Systemic conditions like sickle cell disease or bleeding disorders
Evaluation of Hematuria
The evaluation of hematuria should include a thorough history, physical examination, urinalysis, and serologic testing, as recommended in the study by Wolfman et al 1. Patients with gross hematuria should have a full urologic workup, given the relatively high pretest probability of cancer or other clinically significant underlying conditions, as stated in the study by Wolfman et al 1. Patients with microhematuria have a low risk of malignancy, but should still undergo evaluation to determine the underlying cause, as noted in the study by Wolfman et al 1. The American College of Physicians provides high-value care advice for the evaluation of hematuria, including confirming heme-positive results of dipstick testing with microscopic urinalysis, referring patients with gross hematuria for further urologic evaluation, and considering urology referral for cystoscopy and imaging in adults with microscopically confirmed hematuria, as stated in the study by the American College of Physicians 1.
From the Research
Causes of Hematuria
The causes of hematuria are diverse and can be broadly categorized into several groups, including:
- Calculus (kidney stones) 2
- Trauma 2
- Tumors (such as bladder, kidney, or prostate cancer) 2, 3, 4
- Vascular causes 2
- Infection (such as urinary tract infection) 3, 5
- Benign prostatic hyperplasia 3
- Glomerular causes (such as various forms of glomerulonephritis) 5
- Nonglomerular causes (such as polycystic kidney disease) 5
- Coagulopathy (such as anticoagulant-induced hematuria) 5
- Urethritis and urethrotrigonitis 5
Classification of Hematuria
Hematuria can be classified as either gross (visible blood in the urine) or microscopic (invisible blood in the urine) 2, 3, 4. Gross hematuria has a higher risk of malignancy, with a risk of over 10% 3. Microscopic hematuria, on the other hand, is more commonly caused by benign conditions such as urinary tract infection or benign prostatic hyperplasia 3.
Evaluation and Management
The evaluation and management of hematuria involve a thorough history and physical examination, laboratory tests, and imaging studies 2, 3, 6. The choice of imaging study depends on the suspected cause of hematuria, but computed tomography (CT) urography is a commonly used modality for evaluating gross hematuria 2. Referral to a urologist or nephrologist may be necessary for further evaluation and management 3, 6.